The question of how the presence of nucleosomal
packing of DNA modifies carcinogen interaction at
specific sites cannot be answered by studies on whole
chromatin or bulk nucleosomes because of the
heterogeneity of DNA sequences in the particles. This
problem was circumvented by constructing nucleosomes that
are homogenous in DNA-histone...
The rainbow trout (Oncorhynchus mykiss) model
of chemical carcinogenesis is becoming increasingly
important as a supplement to rodent studies. However,
much of the molecular biology of the carcinogenic
response is still unknown in the trout model. The ras
gene family has been implicated in the tumorigenesis of
both spontaneous and...
For ras gene mutation analysis in the rainbow trout (Oncorhynchus
mykiss) model system, a partial trout ras sequence was identified
using the polymerase chain reaction (PCR). Two synthetic
oligonucleotides based on rat K-ras gene sequence were used as
primers for the PCR procedure. A 90 base pair (bp) sequence,
referred...
Chlorophyllin (CHL), a water-soluble derivative of the green plant pigment, chlorophyll, is an effective antimutagen and anticarcinogen in various model systems when used as a modulator against a class of carcinogens that, in general, have a structure consisting of at least three fused rings. Dibenzo[a,l]pyrene (DBP), an extremely potent environmental...
Dimethylbenz (a) anthracene (EMBA), a carcinogen that requires
metabolic activation to produce active metabolites capable of
binding to DNA, has been studied in the trout and other fish.
Polycyclic aromatic hydrocarbons (PAH) are of importance as they
are ubiquitous in the environment and their carcinogenic effects
in fish from contaminated...
Indole-3-carbinol (I3C) inhibits chemically induced tumor
formation in rodents and rainbow trout. This study examines the
effect of I3C and its analog, indole-3-acetonitrile (I3N) on
xenobiotic-metabolizing enzyme systems. The modulation of these enzyme
systems have been shown to have significant effects on the
interaction of chemical carcinogens and cellular constituents....
A digoxigenin-labeled nonradioactive detection system was used
to screen a zebrafish cDNA library for p53-like and ras-like genes.
One clone was isolated and identified as an incomplete p53-like
gene. The insert size of this clone is 1777 bp, which encodes part of
evolutionarily conserved region II and all of regions...
In rodent models as well as in fish models there are significant
species differences in the susceptibility toward aflatoxin B₁ (AFB₁)
carcinogenesis. Mouse is less susceptible toward AFB₁ carcinogenesis
than rat. Researchers have come to the conclusion that the lower
susceptibility of mice is not a result of less effective...
Indole-3-carbinol (I3C) and butylated hydroxyanisole (BHA), anti-carcinogens
present in the human diet, were tested for their in vivo
and in vitro effect on aflatoxin B₁. (AFB₁) metabolism, and DNA adduct
formation in the rainbow trout. Dietary BHA at either 0.3 or 0.03%
had no effect on the hepatic tumor incidence...
Previous work (Thorgaard, G. H. et al., Aquatic Toxicology 46:121-126, 1999)
showed triploid rainbow trout (0. mykiss) given embryonic carcinogen bath exposures
had significant reduction of induced tumors relative to diploids. In the present study,
trout were made triploid by thermal shock after fertilization. At age of 5 months they...
Previous reports indicate the presence of multiple CYP1A sequences in rainbow
trout, but their functional differences are unknown. This report describes the cloning and partial characterization of four trout CYP1A cDNAs, which are given the tentative
designations CYP1A1v2, v3, v4, and v5. Comparison among these four and three
previously reported...
RNA isolated from BAI strain A (Myeloblastosis) Avian Tumor
Virus can be fractionated into two fractions on a sucrose density
gradient, one of higher molecular weight and one of low molecular
weight. The low molecular weight (LMW) virus RNA was found to
chromatograph the same as E. coli tRNA on...
Avian myeloblastosis virus RNA was fractionated into a high
molecular weight RNA and a low molecular weight RNA fraction by
sucrose density centrifugation. The larger RNA component had a
sedimentation constant of 65S and the low molecular weight RNA
about 4S. The low molecular RNA has two biological properties of...
The genome of the nuclear polyhedrosis virus which infects the
larvae of the tussock moth, the lepidopteran, Hemerocampa
pseudotsugata, was isolated, identified as deoxyribonucleic acid, and
characterized in terms of its physical and biological properties. An
isolation procedure for the viral DNA was established which consisted
of the following steps:...
RNA tumor viruses, such as avian myeloblastosis virus (AMV)
and MC29 virus, cause malignant transformation of the cells they infect.
Transformed cells are able to continually produce progeny virus
particles.
Evidence is given that RNA-dependent RNA polymerase is present
in virus infected cells. RNA-dependent RNA polymerase isolated
from AMV-infected myeloblasts...
There is good evidence that the infection with avian myeloblastosis
virus BAI strain A causes myeloblasts to retain their primitive
nature. These cells are able to multiply and produce virus at a relatively
constant rate. From these observations, a major problem develops
in the study of the virus-induced leukemia, that...
Chicken embryonic cells (CEC) cultured in vitro were able to
withstand the toxicity of DDT at concentrations below 10μg/ml culture
medium. When the DDT concentration exceeded the toxic level, CEC
appeared vacuolated and lost the spindle-like fibroblastic appearance,
Gas chromatographic analysis had shown that the uptake of DDT (3μg/
ml'culture...
Chromatin DNA sequences intimately associated with the "core"
of the basic, repeating chromatin subunit are shown to be relatively
resistant to digestion by micrococcal nuclease. Chromatin DNA
sequences lying between adjacent chromatin subunits, as well as
DNA sequences in regions of chromatin which are free of chromatin
subunits, are subject...
The cytolytic properties of the mosquitocidal 25 Kd protein deltaendotoxin of Bacillus thuringiensis subsp. israelensis (Bti) was studied using the human erythrocyte as a target cell. Both a fixedtime and a kinetic hemolytic bioassay were developed in order to screen a variety of treatments for their influence on the toxinerythrocyte...
The genome of the multicapsid nuclear polyhedrosis virus of
Orgyia pseudotsugata (OpMNPV) was mapped by examining overlapping
Hindlll fragments from cosmid clones which had been constructed
from partial Hindlll digests of viral DNA. Five OpMNPV cosmid
clones containing fragments encompassing the entire OpMNPV genome
were hybridized to blots of DNA...